Endocrine Abstracts

Objective: To investigate factors associated with the presence and growth rate of thyroid nodules(TN) in patients with acromegaly.

Methods: We retrospectively evaluated the medical records of 52 patients with acromegaly followed in our institution (University Hospital Ramón y Cajal). The frequencies of TN and papillary thyroid cancer (PTC) and potential factors associated with nodular thyroid disease (NTD) were investigated. In patients with NTD (n = 25) the first and last ultrasound performed were evaluated. The mean follow up period in these patients was 62.9 (s.d. = 44.4) months. The changes in nodule size comparing with the initial study and the potential factors affecting nodule growth were investigated. The statistical analysis was performed with STATA15.0.

Results: The mean age of the cohort was 50.2 years (SD = 15.90) and 71% (n = 37) were females. At diagnosis, 48.1% of the patients had TN (21 females/four males), and the mean size of the dominant nodules (MSN) was 16.1 (s.d. = 13.013) mm. TN were more commonly found among women (56.8% vs 26.7%, P = 0.049), and patients with IGF1 above the upper limit of normal (ULN) (71.4% vs 28.6%, P = 0.043). No associations were found with age (P = 0.769), IGF1 levels (P = 0.127), macroadenoma (P = 0.089), surgical cure (P = 0.76), thyroid function(P = 0.612), obesity (P = 0.792) or other comorbidities. No correlation was found between MSN and IGF1 or TSH levels (P > 0.05 for r2). During follow up, the mean nodule growth was 1.5 (s.d. = 8.38) mm, the mean nodule growth/year was 1.40 (s.d. = 4.91) mm, and only 5 patients experienced significant growth (> 2 mm) at the end of the follow up. At last visit, nodule growth was similar in uncured vs cured patients (P = 0.317). Neither differences were found according to thyroid function (P = 0.122) or months with IGF1 above normal range (P = 0.057). No correlations were found between growth and IGF1 at the time of ultrasounds(r₂ = 0.429, P = 0.126), thyroid function (r₂ = 0.055, P = 0.851) or other parameters. At diagnosis fine needle aspiration (FNA) cytology was done in 13 patients, 11 were classified as benign (Bethesda category II, B2) and 2 as atypia of undetermined significance (Bethesda category III, B3). During follow up, FNA was repeated in 5 patients: cytology was B2 in all 3 patients with initial B2 rebiopsied due to significant growth, and remained indeterminate(one B3 and one B4) in the two nodules with initial B3 cytology. Seven patients were operated: 4 due to compressive multinodular goiter, 1 due to significant TN growth (+29 mm), and 2 due to indeterminate cytology. PTC was diagnosed only in the B3 patient (microPTC).

Conclusion: We found that NTD is frequent in acromegalic patients, especially in women and patients with elevated levels of IGF1. During follow up, TN growth was infrequent and seemed to be unrelated to acromegaly activity status and thyroid function. The prevalence of PTC was 1.9% in our acromegaly cohort.